Merge tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / arch / arm64 / include / asm / uaccess.h

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index c47257c..55d0adb 100644 (file)
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -21,6 +21,7 @@
 /*
  * User space memory access functions
  */
+#include <linux/bitops.h>
 #include <linux/kasan-checks.h>
 #include <linux/string.h>
 #include <linux/thread_info.h>
@@ -102,6 +103,13 @@ static inline void set_fs(mm_segment_t fs)
        flag;                                                           \
 })
 
+/*
+ * When dealing with data aborts or instruction traps we may end up with
+ * a tagged userland pointer. Clear the tag to get a sane pointer to pass
+ * on to access_ok(), for instance.
+ */
+#define untagged_addr(addr)            sign_extend64(addr, 55)
+
 #define access_ok(type, addr, size)    __range_ok(addr, size)
 #define user_addr_max                  get_fs
 
@@ -278,14 +286,16 @@ static inline unsigned long __must_check __copy_to_user(void __user *to, const v
 
 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 {
+       unsigned long res = n;
        kasan_check_write(to, n);
 
        if (access_ok(VERIFY_READ, from, n)) {
                check_object_size(to, n, false);
-               n = __arch_copy_from_user(to, from, n);
-       } else /* security hole - plug it */
-               memset(to, 0, n);
-       return n;
+               res = __arch_copy_from_user(to, from, n);
+       }
+       if (unlikely(res))
+               memset(to + (n - res), 0, res);
+       return res;
 }
 
 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)